1. Field of the Invention
The present invention relates to nanotechnology, and particularly to functionalized silica for the synthesis of metal nanoparticles.
2. Description of the Related Art
In recent years, nanotechnology has gained enormous scientific progress in the field of research and technology. Nanotechnology is usually used for studying and application of nanoparticles, which can be used in different fields, such as physics, chemistry, biology, and material science, and other promising fields. Currently, there are almost two thousand nanotechnology-based consumer products according to an analysis by Nanotechproject.com. Among all the nano-products, almost 25% products are impregnated with nano-sized silver.
Silver nanoparticles (AgNPs) are used in a wide range of applications, including pharmaceuticals, cosmetics, medical devices, food ware, clothing and water purification, among other uses, due to their antimicrobial properties. A variety of preparation routes have been reported for the preparation of silver nanoparticles. Notable examples include biological methods, photoreduction, and reduction of silver salts by different chemical reductants, such as ascorbic acid, sodium citrate, hydrazine, sodium borohydride, or some solvents, including EtOH and DMF. For protection of silver nanoparticles by silica gel, various methods are reported, including photoreduction and ultrasound.
Among all the synthetic methods, chemical reduction is most commonly used. However, toxic compounds, such as borohydride, are usually involved. Studies have focused on the green synthetic approaches to avoid using hazardous materials. Environmentally benign monosaccharides and polysaccharides are used to reduce the Ag (NH3)2+ complexes formed by reacting AgNO3 with ammonia to AgNPs. Previous studies have produced AgNPs with sizes ranging from 50-200 nm and silver hydrosols ranging from 20-50 nm. However, aggregation during synthesis can hinder the production of AgNPs with small and uniform sizes. The control of their size, shape, dispersity, and in particular, the combination of metal nanoparticles with a specific heterogeneous support, is essential to prevent aggregation and/or coalescence, to obtain enhanced activity and selectivity in a desired application. Recently, some researches have reported the synthesis of silver nanoparticles immobilized on silica gel, which provides good solid support for adsorption due to its chemical, thermal, and mechanical stability.
Thus, silica support functionalized with triazine-hydrazino derivatives for preparing metal nanoparticles thereby solving the aforementioned problems are desired.